To be fair, I might be being a bit melodramatic. Up until this DLC this game has by and large been vastly less challenging than Dark Souls 1, and to have such a drastic spike in difficulty is kind of jarring. In hindsight I'm not sure I'd say this place has been much more difficult than say my first trip thru Blighttown, or trying to pass the snipers in Anor Londo. It has been fun and rewarding to explore.
I just beat the first boss in here, who happened to take practically zero damage from my hexes, so yay, yet another way the class I decided to play the entire game as getting fucked by design decisions, but whatever, I had enough summon help that I was able to pass it in a few tries.